The present invention relates to a system for controlling the intake air for an automotive engine, and more particularly to a system for controlling swirling of the intake air in a combustion chamber of the engine.
In order to improve the combustion efficiency and fuel consumption of an automotive engine, the engine is constructed to cause the induced air to swirl in the combustion chamber. The swirling can be generated, for example, by disposing an intake port in a cylinder head in the tangential direction with respect to the corresponding cylinder. In conventional swirl generating means, swirl ratio (rotational speed of swirl/engine speed) is set to a constant value irrespective of driving conditions of a vehicle. Assuming that the swirl ratio is set at a value proper for a middle load on an engine between light and heavy loads, the swirl at the set swirl ratio is insufficient for a light load, and excessive for a heavy load. Accordingly, by such constant swirl generating means, fuel consumption is not improved because the combustion deteriorates caused by the insufficient swirl ratio and the cooling loss increases caused by a high swirl ratio.
Japanese Utility Model Laid Open No. 56-142227 discloses a control system in which a deflector plate is provided in an intake port. The disposition of the deflector plate is adapted to be changed in angle with respect to the axis of the intake port in accordance with engine operating conditions such as load and engine speed, so that the above-described deficiency may be eliminated. However, the system can not improve the combustion efficiency in particular operating conditions such as transient state, high EGR rate and others.